The present invention relates to a printer, and particularly to a frame line inserting circuit for inserting a frame line around the printing area during printing in a printer.
Generally, a video color printer is an apparatus for receiving and printing color video signals. FIG. 1 illustrates an example of a structure of such a conventional video color printer. Referring to this drawing, an A/D converter 1 converts the received analog video signals to digital video signals. A line memory 2 stores the output digital video data from the A/D converter 1, as the unit of the line. Further, a gradation read only memory (ROM) 3 stores temperature compensating data corresponding to the status of emitting heat of a TPH (thermal print head) 6. A comparator 4 which receives the video data of the line memory 2 and the compensated data of the gradation ROM 3 compares the two data so as to compensate the density of the received video data. Consequently, the TPH 6 can perform printing at a constant density regardless of the status of the emitting heat. Under this condition, if the TPH 6 has two arrays, a dividing circuit 5 performs such a function that the video data for the respective lines are divided in such a manner as to be applied to the respective arrays of the TPH 6. If the TPH 6 has a single array, the dividing circuit 5 is not used. However, the printing method as described above is capable of printing only the video signals, and therefore, there is the disadvantage that the boundary of the print is not definite. That is, the boundary status between the printing area and the non-printing area becomes not neat.